Detritus is believed to play a significant role in coral reef food webs, but its nutritional value is not well resolved. For my thesis, I measured the deposition rates and composition of detritus collected in sediment traps (trapped particulate matter, TPM) in more detail than in any previous study to allow a better estimate of the potential nutritional value of detritus to coral reef inhabitants. Over a three-year period (March 1996 – March 1999), TPM sedimenting onto fore-reef slope habitats was collected in sediment traps deployed at depths between 10-22m on the fore-reef slope of coral reefs located along a coastal to oceanic (nearshore/offshore) gradient in the Great Barrier Reef (GBR) and Bermuda platform. Based on the results of this thesis it can be concluded that there are clear nearshore/offshore (cross-shelf) gradients in the composition and depositional fluxes of coral reef detritus. Shallower, more coastal reefs will tend to have larger quantities of lower quality detritus because of greater mixing with resuspended sediment than those further offshore. The lack of any overt evidence of terrestrial organic matter in TPM, even at a nearshore site downstream of a river mouth, indicate that nutrients are not entering nearshore reef food webs as organic detritus. The average POC content of TPM was low (~2 % of dry weight) comprised of <59% labile carbon, which was dominated by carbohydrates and contained < 30% labile nitrogen (proportion of protein to total nitrogen). Less reactive lipid biomarkers (sterols, alcohols and saturated fatty acids) dominated in TPM. These nutritional characteristics indicate that detritus is intermediatery in nutritional value when compared to labile live food sources (phytoplankton, zooplankton) and refractory sediment organic matter. The intermediatery composition of TPM to live food and refractory sediment organic matter suggest that organisms with a high energy diet (live organisms) cannot survive solely on detritus but may supplement their diet with detritus to overcome temporary energy deficits. In contrast, organisms with a low energy diet (sediment feeders) may benefit from consuming newly settled detritus. The lowest fluxes of detrital macronutrients recorded in this study (i.e. outer-shelf GBR and Bermuda sites) were > 250mg POC, > 35mg PN and > 2.4mg PP m^-2 day^-1). This detrital macronutrient flux is equivalent to half of the mean carbon supplied by phytoplankton productivity or benthic community production (~500mg C m^-2 day^-1) to reef food webs and more than double the nitrogen from nitrogen fixation (~5mg N m^-2 day^-1) These results confirm that detritus is an important source of nutrition in reef food webs.